In airborne radar systems, where the radar itself is in motion, and it is desired to detect and track objects moving on the ground, such objects must be distinguished from ground clutter. Since the radar is in motion, the clutter appears to be in motion relative to the radar, and the doppler effect shifts the frequency of the clutter echo signal. Thus, the closer the relative velocity of the clutter is to that of the target, the more difficult it is to distinguish between such clutter and the target. Also, in airborne radar systems, designed to detect moving targets on the ground, this motion of the airborne platform causes the clutter from different parts of the antenna beam to spread across the doppler spectrum. This limits the minimum velocity at which moving targets can be detected and/or tracked. Therefore, difficulty is encountered in attempting to distinguish between ground clutter and targets that move slowly, such as in the order of three knots, for example.
Thus, it is desirable to be able to provide a method for detecting and tracking slowly moving targets in the presence of ground clutter by an airborne radar.